Blog

Home > Asset Tracking: Matching GNSS + Cellular to Battery Life
You are currently viewing Asset Tracking: Matching GNSS + Cellular to Battery Life

Asset Tracking: Matching GNSS + Cellular to Battery Life

Asset Tracking: Matching GNSS + Cellular to Battery Life

An asset tracker is a battery with a radio strapped to a pallet. It does two things: it works out where it is, and it tells someone. The first needs a GNSS receiver. The second needs cellular. Both draw from the same battery, and neither cares about your datasheet’s sleep current.

The number that matters is how long the whole thing runs between charges, and that is a duty-cycle question, not a chip-question.

The two radios, one battery

The GNSS side has to find satellites, take a fix, and go quiet. The cellular side has to wake, attach, send its few bytes, and sleep. A module that is “low power” on the sheet means little if the firmware wakes it every few minutes to splash a position across the network.

On the GNSS side, the u-blox MAX-M10 draws under 25 mW in continuous tracking while listening to GPS, GLONASS, Galileo and BeiDou at once. That low tracking power is why it keeps showing up in battery trackers. The Sierra XS1110 is a similar ultra-low-power multi-GNSS option. On the cellular side, NB-IoT and LTE-M exist for exactly this: power saving mode and extended DRX let a chip sleep for long, predictable stretches and wake on a schedule.

The duty cycle is the real spec

Battery life is capacity divided by average current, and average current is set by duty cycle. A tracker that reports once a day is a different product from one that reports every 15 minutes, even with the same module.

The numbers back this up. A Lansitec container tracker runs two 4,000 mAh lithium batteries for up to five years at a 30-minute reporting interval. The Jimi IoT LL701, built on the Nordic nRF9160, runs off one to three CR123A cells and still reaches about five years depending on mode. A fleet tracker such as the Manta Fusion gets ten plus years on daily updates, about five years on motion-based reporting, and roughly four years on hourly updates.

So the lesson is simple: when you ask for a battery estimate, give the report interval. “We need a long battery” is not a spec. “We send one position a day with a wake window under a second” is.

GNSS duty matters more than people expect

In many trackers the GNSS fix, not the cellular transmission, is the bigger surge inside the wake window. A cold start can take tens of seconds and several hundred millijoules, while a well-assisted hot fix is far cheaper.

The practical tricks are to use assisted GNSS or a coarse cell-ID position for the first pass, then refine with the satellite fix, and to keep the receiver asleep until the device actually needs a location. Choose a GNSS module with low tracking power and a fast time-to-first-fix, and multi-constellation support so a trailer in a container yard or under a canopy still locks. The Quectel L76 and L29D families sit in that spot.

Which cellular tier

  • NB-IoT: static assets, deep indoor and underground, tiny data. Best battery life and penetration, but low throughput and latency. Great for a pallet that sits in a warehouse and reports once a day.
  • LTE-M (Cat-M1): the practical default for trackers that move. Higher throughput, lower latency, better roaming, and good power efficiency. It handles firmware updates and more frequent reports without burning the battery. The BC92 is an NB-IoT and GSM dual-mode part for regions still leaning on 2G; the LPWAN guide walks through NB-IoT against LTE-M and LoRaWAN.
  • Cat-1 bis and Cat-4: fine when a tracker streams or needs near-real-time, but they cost more power. Use them when the product is really a telematics box, not a battery tracker.

For fleets that cross borders, an eSIM with remote provisioning lets the module switch operators without touching hardware. The eSIM guide covers what to check on the module.

The design checklist

  1. Set the report interval first, then size the battery from the measured duty cycle, not from the sleep current alone.
  2. Make the GNSS fix cheap. Assisted or coarse-position fallback, multi-constellation, and a module with fast time-to-first-fix.
  3. Place the antennas properly. GNSS needs sky view, usually with an active antenna and LNA; cellular needs band coverage across the enclosure. Test in a real trailer, not on a bench.
  4. Model temperature. Lithium thionyl chloride cells derate in the cold, and a container on a truck in winter is not a lab.
  5. Fit an eUICC for multi-operator or multi-country fleets.
  6. If the asset moves on the road, lean LTE-M; if it sits in a rack or a warehouse, lean NB-IoT.

When GNSS plus cellular is the wrong answer

If the asset stays indoors in a fixed facility, a BLE, Wi-Fi, or UWB ranging solution is cheaper and more accurate than a satellite fix. If you already run LoRa gateways and want no per-SIM cost, LoRaWAN is reasonable. And if the product needs a live map feed, that is a telematics device, and the battery estimate changes entirely.

The short version

Match the radio pair to how the asset moves and how often it reports, and the battery life follows. The sleep current on the sheet is not the spec. The duty cycle is. Write the brief that way, and a multi-year tracker stops being a marketing claim and becomes a design target.

We carry GNSS modules from Quectel, u-blox, Sierra and SIMCom, and NB-IoT and LTE cellular modules, so we can match the radio pair to your report interval and battery budget. Send your BOM or describe the tracker you are building, and we will tell you which GNSS and cellular combo fits.

Send us your BOM

Sources

Tags: , , , , , ,